数据结构和算法--队列的链式实现

//队列链式队列的实现

#include <stdio.h>
#include <stdlib.h>

//定义数据类型
typedef int datatype_t;

//定义结构体
typedef struct node{
datatype_t data;
struct node *next;
}linknode_t;

typedef struct{
linknode_t *front;
linknode_t *rear;
}linkqueue_t;

//创建一个空的队列
linkqueue_t *linkqueue_create()
{
linkqueue_t *lq = (linkqueue_t *)malloc(sizeof(linkqueue_t));
lq->front = lq->rear = (linknode_t *)malloc(sizeof(linknode_t));

lq->front->next = NULL;

return lq;
}

//入队
int linkqueue_input(linkqueue_t *lq, datatype_t value)
{
linknode_t *temp = (linknode_t *)malloc(sizeof(linknode_t));
temp->data = value;
temp->next = NULL;

lq->rear->next = temp; //将入队的结点插入到rear后面
lq->rear = temp;    //将raer后移
//lq->rear = lq->rear->next;

return 0;
}

//判断队列是否为空
int linkqueue_empty(linkqueue_t *lq)
{
return lq->front == lq->rear ? 1 : 0;
}

//出队（删除头结点）
datatype_t linkqueue_output_del(linkqueue_t *lq)
{
linknode_t *temp = NULL;
datatype_t value;

if(linkqueue_e
4000
mpty(lq))
{
printf("linkqueue is empty\n");
return (datatype_t)-1;
}

temp = lq->front;  //将要删除的头结点的地址赋值给temp
lq->front = lq->front->next; //front往后移，并且获取数据
value = lq->front->data;

free(temp);
temp = NULL;

return value;
}

//出队（保留头结点）
datatype_t linkqueue_output_undel(linkqueue_t *lq)
{
linknode_t *temp = NULL;
datatype_t value;

if(linkqueue_empty(lq))
{
printf("linkqueue is empty\n");
return (datatype_t)-1;
}

temp = lq->front->next;
lq->front->next = temp->next;

value = temp->data;

free(temp);
temp = NULL;

if(lq->front->next == NULL)
{
lq->rear = lq->front;
}

return value;
}

int main(int argc, const char *argv[])
{
linkqueue_t *lq = linkqueue_create();

linkqueue_input(lq, 10);
linkqueue_input(lq, 20);
linkqueue_input(lq, 30);
linkqueue_input(lq, 40);
linkqueue_input(lq, 50);

printf("del = %d\n", linkqueue_output_undel(lq));
printf("del = %d\n", linkqueue_output_undel(lq));
printf("del = %d\n", linkqueue_output_undel(lq));
printf("del = %d\n", linkqueue_output_undel(lq));
printf("del = %d\n", linkqueue_output_undel(lq));

linkqueue_input(lq, 10);
linkqueue_input(lq, 20);
linkqueue_input(lq, 30);
linkqueue_input(lq, 40);
linkqueue_input(lq, 50);

printf("del = %d\n", linkqueue_output_del(lq));
printf("del = %d\n", linkqueue_output_del(lq));
printf("del = %d\n", linkqueue_output_del(lq));
printf("del = %d\n", linkqueue_output_undel(lq));
printf("del = %d\n", linkqueue_output_undel(lq));

return 0;
}